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usort() function producing bad results on a linux environment, ok on windows

Posted on 2009-07-08
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Last Modified: 2012-05-07
This is really weird, the same code works on windows, but not on linux.

When I run the code below on a windows machine with PHP 5.2.5, it works perfect, I get the output array alphabetically ordered.

When I run it on a linux box running PHP 5.1.6 I get an array that doesn't have the same order as the original array, but it is also not properly sorted.

Do you guys know what part of my code is "environment dependant"? I can hardly believe the same code will produce two different results in different platforms...


// The code here:
 

class TestTwo{
 

                      // This is just the contructor / driver:

	function TestTwo(){
 

                                          // bootstrapping the input array:

		$sort_array = file_get_contents('test_array_sort.txt');

		$attributes_array = unserialize($sort_array);
 

		$this->attributes_array_sorted = $this->createAttributesArraySorted($attributes_array);			

                                          // At this point, I get the right output on Windows, and the badly sorted array in Linux

	}

	

	private function createAttributesArraySorted($attributes_array_){

		

		foreach($attributes_array_ as &$val){
 

			usort($val['children_nodes'], 'TestTwo::cpm_node');
 

		}

		return $attributes_array_;

		

	} /* end private function createAttributesArraySorted($attributes_array_) */

	

    /*

     * Auxiliary function used to sort attributes in alphabetical order 

     */

    static function cpm_node($a,$b){

    	

    	return strcasecmp($a['node_name'], $b['node_name']);
 

    } /* end static function cpm_nodes() */

    

} /* end class TestTwo */

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Question by:cabrera48
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4 Comments
 

Author Comment

by:cabrera48
ID: 24809757
A bit more of information: it looks like the cpm_node() function never gets called on linux.

I put a print statement inside of it, and I can see the print output on windows, on linux it doesn't display.

So the problem seem to be in this line:

usort($val['children_nodes'], 'TestTwo::cpm_node');
 
Why would that fail to call TestTwo::cpm_node static function on linux?
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LVL 27

Accepted Solution

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ddrudik earned 500 total points
ID: 24814811
See the comments on static method calls/versions here:
http://us3.php.net/manual/en/language.pseudo-types.php#language.types.callback
appears that you are using a version prior to 5.2.3:
array('TestTwo', 'cpm_node')

Although I didn't test the above.
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Author Comment

by:cabrera48
ID: 24815390
You are right, that was the problem, nothing to do with linux, but the PHP version I was using there.

Thank you.
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LVL 27

Expert Comment

by:ddrudik
ID: 24816396
Thanks for the question and the points.
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